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2-8
DivisionEquations
Equations
2-8 Division
Warm Up
Problem of the Day
Lesson Presentation
Course
Course 11
2-8 Division Equations
Warm Up
Solve.
1. 5x = 20
x=4
2. 7n = 84
n = 12
3. 18 = y – 4 y = 22
4. 21 = n + 3 n = 18
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1
Course
2-8 Division Equations
Problem of the Day
If 11 is 4 less than 3 times a number, what
is the number?
5
Course 1
2-8 Division Equations
Learn to solve whole-number division
equations.
Course 1
2-8 Division Equations
Multiplication is the inverse of division.
When an equation contains division, use
multiplication to “undo” the division.
Course 1
2-8 Division Equations
Additional Example 1A: Solving Division Equations
Solve the equation. Check your answer.
x
=5
7
x =5
7
7 x = 7 5
7
x = 35
Check
x =5
7
?
35 =
5
7
?
5 = 5
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x is divided by 7.
Multiply both sides by 7 to
undo the division.
Substitute 35 for x in the equation.
35 is the solution.
2-8 Division Equations
Additional Example 1B: Solving Division Equations
Solve the equation. Check your answer.
13 = p
6
13 = p
p is divided by 6.
6
6  13 = 6  p
Multiply both sides by 6 to
6
undo the division.
78 = p
p
Check 13 =
6
?
13 = 78 Substitute 78 for p in the equation.
6
?
13 = 13  78 is the solution.
Course 1
2-8 Division Equations
Check It Out: Example 1A
Solve
x
2
x
2
2 x
2
x
Check
the equation. Check your answer.
=9
=9
x is divided by 2.
= 2 9
Multiply both sides by 2 to
undo the division.
= 18
x =9
2
?
18 =
9
2
?
9 = 9
Course 1
Substitute 18 for x in the equation.
18 is the solution.
2-8 Division Equations
Check It Out: Example 1B
Solve the equation. Check your answer.
72 = p
4
72 = p
p is divided by 4.
4
4  72 = 4  p
Multiply both sides by 4 to
4
undo the division.
288 = p
p
Check 72 =
4
?
72 = 288 Substitute 288 for p in the equation.
4
?
72 = 72 288 is the solution.
Course 1
2-8 Division Equations
Additional Example 2: Application
At Elk Meadows Park an aspen tree is onethird the height of a pine tree.
height of aspen = height of pine
3
The aspen tree is 14 feet tall. How tall is the
pine tree?
Let h represent the height of the pine tree.
Substitute 14 for height of
14 = h
3
aspen. h is divided by 3.
Multiply both sides by 3 to
3  14 = 3  h
3
undo the division.
42 = h
The pine tree is 42 feet tall.
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2-8 Division Equations
Check It Out: Example 2
Jamie weighs one-half as much as her father.
Jamie’s weight = father’s weight
2
Jamie weighs 95 pounds. How many pounds
does her father weigh?
Let w represent her father’s weight.
Substitute 95 for Jamie’s
95 = w
2
weight. w is divided by 2.
2  95 = 2  w
Multiply both sides by 2 to
2
undo the division.
190 = w
Jamie’s father weighs 190 pounds.
Course 1
2-8 Division Equations
Lesson Quiz
Solve each equation. Check your answers.
1. x = 7 x = 70
10
2. 8 = x
x = 32
4
3. x = 11 x = 99
9
4. x = 7 x = 105
15
5. The area of Sherry’s flower garden is onefourth the area of her vegetable garden. The
area of the flower garden is 17 square feet. Let x
represent the area of her vegetable garden. Find
the area of her vegetable garden? 68 square feet
Course 1